The bottom line. If you start out as a beginner and spend an average of 1 hour per day working on your Spanish, you should able to reach conversational fluency within 8 – 12 months.
That translates to roughly 250 – 350 hours of time spent. My recommendation after teaching an tutoring for over 20 years is that you start your Spanish studies with two tutoring sessions per week to achieve the intermediate high level in six months.

Learning a language in college can greatly improve your career opportunities.
Options for language learning include majoring, minoring, electives, or studying abroad. Popular industries for language majors include foreign relations, tourism, and marketing.

The US Department of State says that it takes an English learner 575–600 class hours.

That's quite a long time!

In case you are doing the math at home that means you would need to work for a little over 10 hours a week for an entire year to achieve Spanish Fluency.